Project 2 will focus on apolipoprotein mimetic peptides. Because these compounds appear to have generalized anti-inflammatory properties, this information is likely to be highly informative of rate-limiting steps in inflammation, as well as in atherogenesis. Aim 1 is to determine the mechanism(s) by which apoA-l mimetic peptides are anti-inflammatory at plasma concentrations that are orders of magnitude less than that of apoA-l. In patients with CHD and pro-inflammatory HDL, a single oral dose of D-4F produced plasma levels of ~4 nanomolar and significantly improved the anti-inflammatory properties of HDL. How could a concentration of ~4 nanomolar of an apoA-l mimetic peptide be effective when the concentration of apoA-l in the patient plasma was -35 micromolar? We hypothesize that the anti-inflammatory properties of apoA-l mimetic peptides derives from their ability to bind pro-inflammatory oxidized lipids with a KD many orders of magnitude less than human apoA-l. We hypothesize that the remarkable anti-inflammatory properties of apoA-l mimetic peptides also relate to their ability to inhibit pro-inflammatory cytokine production while not inhibiting the induction of anti-oxidant enzymes such as heme oxygenase-1 (HO-1). Aim 2 is to investigate the mechanism(s) by which apolipoprotein mimetic peptides reduce the content of heme-binding and hemecontaining proteins in HDL and reduce vascular inflammation. Administration of an apoA-l mimetic peptide dramatically reduced these HDL-associated proteins. We hypothesize that the binding of these proteins to HDL causes iron to enter macrophages via pathways that stimulate the production of pro-inflammatory cytokines without stimulating anti-oxidant enzymes such as HO-1. We hypothesize that apoA-l mimetic peptides reduce the binding molecules in HDL for iron containing proteins, thus shifting these iron containing proteins away from HDL and allowing them to enter macrophages by pathways that do not stimulate proinflammatory cytokines but which do induce HO-1. Aim 3 is to determine.the mechanism(s) by which niclosamide enables apolipoprotein mimetic peptides synthesized from all L-amino acids to be bioactive when administered orally. Aim 4 is to determine the mechanism(s) by which apolipoprotein mimetic peptides promote apoA-l synthesis in the intestine.